The present invention relates to improved weft sensor mechanism for fluid jet looms, and more particularly relates to improvement in construction of a weft sensor mechanism in which a plurality of electrode or photocell type sensors are arranged on the arrival side of wefts facing the running path of the wefts.
On a weaving loom equipped with the conventional weft sensor mechanism of the electrode type, a pair of electrode type sensors are mounted to the reed end on the arrival side of weft facing the running path of the wefts in order to detect success in weft insertion. The sensors or feelers are properly spaced from each other along the running path of the wefts and both are coupled to a common given electric detection circuit.
When weft insertion is carried out normally, the leading end portion of a weft safely reaches the arrival side of wefts and comes in contact with both feelers, the two feelers are electrically connected to each other, and the detection circuit judges that weft insertion has been carried out normally.
When weft insertion is carried out abnormally, the leading end portion of a weft does not safely reach the arrival side of weft, the two feelers are left electrically disconnected from each other, and the detection circuit judges that weft insertion has been carried out abnormally in order to generate a signal to stop running of the loom.
So far as the above-described situations are concerned, there is no problem with the conventional sensor mechanism. Trouble starts when weft breakage happens at or near the midpoint of the weaving width. In this case, the leading end portion of a weft per se safely reaches the arrival side of wefts and the pair of feelers are electrically connected to each other just as they are when weft insertion has been carried out normally. Thus, the detection circuit judges that weft insertion has been carried out normally and the loom goes on running although, actually, weft insertion could not be carried out normally due to the intermediate weft breakage.
This misjudgement by the conventional weft sensor mechanism apparently results in production of a woven cloth including serious weaving defects. In order to remove the weaving defects, considerably time- and labor-consuming work for repair is required.